Various power line sensors are disclosed in the prior art. For example, reference U.S. Pat. Nos.: 3,428,896; 3,633,191; 4,158,810; 4,268,818; 4,724,381; 4,799,005; and 4,808,917. In general, all of these sensors have been proposed for dynamic line rating of electrical power and are designed to be permanently installed on high voltage transmission lines. The typical transmission line sensor available in the prior art measures quantities associated with operation of the overhead line such as voltage on the conductor, current flow in the conductor, conductor temperature and ambient temperature. This information is gathered and transmitted to a local ground receiver. Data from various ground receivers is ultimately transmitted to a central control station where the information is analyzed. Based on this analysis, the entire power transmission system is controlled with power being supplied to the various transmission lines in accordance with the measured parameters.
Although existing sensors for monitoring high voltage transmission lines are of interest, the present invention addresses a different problem. Specifically, a need exists in the utility industry for a portable, pole/line installed sensor and parameter collection system to measure individual customer service electric energy consumption at the secondary level. The purpose of such a sensor is to accumulate a power consumption history in kilowatt-hours for comparison with readings from the customer's existing entrance meter as a means of detecting possible meter tampering.
Existing transmission line sensors have a number of inherent drawbacks when considered as monitors for uncovering customer meter tampering. For example, most prior sensors are physically cumbersome, employing large clamp-on ammeters. Existing sensors typically require considerable time to install, which in combination with their sprawling bulkiness would draw attention to the sensor and alert a customer that secondary monitoring is occurring. Typically, existing voltage connections require additional wires that must be connected to live service conductors. Further, care must be taken to connect such voltage wires to the conductors in a correct order; and there is no simple way to tell if conductors have been connected properly. In addition, kilowatt-hour readings of the monitoring system would have to be taken at the same time as the customer's meter reading in order to correlate the two readings.
Thus, the present invention comprises a new secondary parameter monitoring and analysis system which overcomes the aforementioned disadvantages of existing high voltage transmission line systems when considered as a secondary load monitoring device. Among the specific objects of the invention, all within the context of systems for collecting and transmitting parameters associated with electrical power line operation employing line-mounted sensor modules, are: a compact sensor unlikely to draw a customer's attention; quick and easy installation, again so as not to draw a customer's attention; good accuracy, i.e., on the same order of accuracy as an entrance meter; avoidance of a need to simultaneously take readings off the monitoring system and the customer's meter; and an ability to accommodate all entrance configurations, including secondary voltages through 480 volts, three-phase, with various service conductor diameters. Further, an ability to report kilowatt-hours within a maximum error of five percent with currents ranging from 1-800 amperes is desired.